Micro-Electro-Mechanical System (MEMS) devices may be used in various applications such as micro-phones, accelerometers, inkjet printers, etc. A commonly used type of MEMS devices utilizes a movable element (sometimes referred to as a proof mass) as a capacitor plate, and a fixed element as the other capacitor plate. The movement of the movable element causes the change in the capacitance of the capacitor. The change in the capacitance may be converted into the change in an electrical signal, and hence the MEMS device may be used as a microphone, an accelerometer, or the like. The movement of the movable element may also be used for squeezing the ink in an inkjet printer.
For most applications, MEMS devices are electrically connected to Application Specific Integrated Circuits (ASICs) to form a complete system. The connections may be made through wire bonding, which requires extra chip areas. The connections may also be made through the substrate, wherein portions of the conductive substrate may be isolated by dielectric materials to form the connections. Complicate process steps are involved in the formation of the dielectric materials that insolate the substrate portions.